the butterfly effect
by sarsaparillia
Summary: Harry Potter is Sorted into Slytherin, and, surprisingly, nothing goes too terribly. — full cast.
1. first floor people

**disclaimer**: disclaimed.  
><strong>dedication<strong>: to Sonya, because she asked.  
><strong>notes<strong>: oh look, another oneshot series.  
><strong>notes2<strong>: hahahahaha kill me

**chapter title**: first floor people  
><strong>summary<strong>: Pansy is the only one with any sense here, not even kidding. — Harry, Draco, Blaise, Pansy, peripheral Draco/Hermione, Slytherin!Harry AU.

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"Hermione's brilliant, you know," Harry said conversationally, one Saturday morning in Febrary as he and Draco and Blaise lounged in the Slytherin Common Room next to the roaring fire. The lake water was a thick sheet of ice against the windows, pale blue-green light filtering down to wash the dungeons in a quiet winter's morning light.

"Since when d'you want in Granger's knickers, then, Potter?" Blaise asked, tipping his head back so that hung comfortably over the edge of the squishy couch he'd flopped down upon.

"Hermione and me? Nah, mate, that'd just end terribly. I'm talking about Drakey over there," Harry said, snickering and nodding towards the blond Slytherin currently bent over the Arithmancy essay he'd been snarling at all evening. He was three feet into it, and apparently that wasn't enough—he was tugging at his hair the way he always did when he got mental about school.

"What about him?"

"Can't even hear us, can he," Harry said rhetorically, waving a hand lazily in Draco's direction. "Look at him, Zabini, good little worker bee he is."

"'Course he is, he's still muttering 'bout that five-foot parchment Vector wanted from him."

"He _can_ hear you," Draco snarled at them, "and _he_ doesn't appreciate your _commentary_, Potter."

"It's not Hermione's fault she's brilliant," Harry said reasonably as he crumpled up a bit of parchment and flung it at Draco's head. "She's just _brilliant_. Would have failed Charms last year without her."

"You're the worst Slytherin ever, Potter," Pansy voice came from behind them. There may have been actual fondness in there, but neither Harry nor Blaise nor Draco really wanted to think about it. Pansy was not known for _fondness_. "What are you on about, anyway?"

"Granger," Blaise said, still hanging near-upside down on the couch. "Potter says Malfoy's got a crush."

Pansy scoffed, flipped the sharp edges of her hair over her shoulder with her hip popped out. "Well, _everyone_ knows that."

Draco sat up, eyes wild as he stared round at the three of them. "_What_?!"

"Everyone knows you wank it to Granger," Pansy yawned at him. "Literally everyone. Even _Daphne_ knows, and that girl's been infatuated with you since, Merlin, I don't even know. So, yeah, everyone," but she paused for a moment to think about it. "Oh, 'cept maybe Granger herself. Girl hasn't a clue—she's blinder than _Ronald_, it's terrible."

"Ron's not blind, he's just…"

"He's _thick_," she said boredly, "I don't know _why_ I like him. Regardless, Granger's blinder than a bat. I love her, but romance is _lost_ on her, poor soul."

"Pans, this _is_ Draco we're talking about," Harry said.

"And he's no better than she is," Pansy said, tossing her head impatiently.

"I am _right here_," Draco snapped, surfacing again from the clutches of his parchment. There was ink on his nose.

"You've got ink on your nose, darling," Pansy sighed. "Just there. It makes you look a little mad. And stop ruffling your hair, you're going to go bald, and _then_ what will people say?"

"Who are you, my mother?!"

"Oh, Merlin, now I've gone and imagined that…"

"Shut it, Zabini!"

Harry choked on his laughter and only barely managed to dodge out of the way of the textbook that Draco had sent flying their way. "Mate, your aim needs work."

"Says the _Seeker_," Draco sneered.

"Have we hurt your feelings, _Your Highness_?"

"Oh, let him alone, he's coming to terms with his crush on Granger. That can't be fun," Pansy said, exasperated, as she plopped herself down between Blaise and Harry, easy as you please.

Harry raised a skeptical eyebrow at her, extracting an arm from beneath a pillow to wrap it around her shoulders. "You got something to tell us, Pans? She _is_ your best friend."

Pansy sniffed at him. "And I went through the horror when I first realized that. Hands off, Potter, lest I tell Weasley."

"Which one?" Harry asked, honest.

"The one you kiss."

"…Yes?"

"Oh, Morgana, how do I even know you? The female one that you stalk around the Greenhouses asking for a date like the pathetic mook you are!"

"Aww, Pans, don't be cruel, it's not his fault he's dim, you gotta be clear with him. After all, Weasley is quite lovely—"

Harry launched himself across Pansy to box Blaise's ears.

It didn't work very well.

But it set Pansy to laughing between them, shoving at Harry to get him off her lap and into Blaise's, where it devolved into the pair of them making kissy faces and batting their eyelashes at each other, just like every other tussle fight they'd ever had. They were almost grown, now, but so little had changed—no one paid them any attention, because this was par for the course. Even the little Firsties where too busy revising for their end-of-semester exams to gawk at Harry Potter and the odds and ends of the upper echelon of Wizarding Society.

(It wasn't very often that you saw Draco Malfoy looking anything less than immaculate, after all.)

"You're all so _distracting_!" Draco exploded at last. "I'm going to the _Library_!"

And then he stomped off, books and paper stuffed haphazardly into his bag, looking harassed.

The door to the common room slammed closed with a _bang_ after he was gone.

Harry, Blaise, and Pansy all winced in unison.

For a long moment, everything was silent.

And then Harry grinned terribly.

"Well, _that_ went well," he said, from the floor where Blaise had finally dumped him.

"What did you do?" Pansy asked, and helped him back up onto the couch where she promptly curled up like a contented cat. "Oh, Harry, you haven't done what I think you have?"

"Ron was working on Hermione," Harry said happily. "If I've got it right, she should be swearing her way down to the Library right 'bout now."

Pansy sat up, eyes narrowing. "Harry Potter, are you trying to set your best friend up with my best friend?"

"Yes?" Harry hazarded, shrinking back from the sudden suspicion in her gaze.

"Oh," Pansy said, and sunk back down. "Well then. Go get me a cup of tea from the kitchens. I'm going to need it for when Draco gets back with lip marks all over his collar."

"Must I?"

"_Go_, Potter, before I catch Draco and tell him what you're up to!"

Harry was gone like a shot to find his Invisibility Cloak before Pansy got truly upset.

"How do you know _that_?" Blaise asked, wrapping himself around her in the space that Harry had left.

"Oh, just something Hermione said," Pansy shrugged one shoulder like a crow before she reached up to pat Blaise on the cheek. "She's quite fond of him, though she doesn't want to be."

"Pans…" Blaise said slowly.

Her laughter filtered through the Common Room, brightly airy. "She had a _hickey_ last I saw her, Blaise. That was _yesterday_, after they fought in Potions, remember?"

Blaise stared down at her, wide-eyed.

"Don't give me that, Zabini, don't tell me you didn't see it coming."

"I—didn't think it would be this soon?"

"No," Pansy grinned, "you did not. By the way, you owe me five galleons. I said they'd snog before Christmas, and I was right."

"That's not fair, you had Harry helping you!"

"Slytherin," she said, still smiling.

Well, Blaise really had nothing to say to that.

And later, when Draco came back to the Common Room, there were, indeed, lip marks on his collar. Pansy hooted her laughter, and Blaise paid up.

Harry tried not to be _too_ vindicated.

—

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_fin_.


	2. built a brand new family

**disclaimer**: disclaimed.  
><strong>dedication<strong>: to Sonya for Christmas 2k14, but late as fuck OOPS SORRY I LOVE YOU  
><strong>notes<strong>: here have some slytherin!Harry bc apparently I have nothing better to do with my life.

**title**: built a brand new family  
><strong>summary<strong>: Petunia Evans has two co-parents, and neither of them are a good influence. — AU; Slytherin!Harry.

—

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Petunia Evans married Vernon Dursley when she was nineteen years old.

Three years later, she would have a son she named Dudley.

A year after that, a second baby tumbled into Petunia's life.

There was a letter that explained very many things attached to the little bundle left on the doorstep of Number 4, Privet Drive on the cool, misty November morning that Petunia Dursley opened the door to fetch the eggs. Of course, that was not the first thing she noticed: there was, after all, a baby boy on the stoop. He had a tuft of very dark hair and a thin scar upon his forehead, but otherwise he differed very little from other children his age.

"What are you doing here? Where's your mum?" she asked softly as she gathered him up. The sound of her voice must have roused him, for he yawned widely—there were the first signs of teeth poking out through his gums, that had to be uncomfortable, poor mite—and then he opened his eyes.

Petunia's heart nearly stopped.

She knew those eyes.

—

"Harry, get the post!"

Harry Potter rolled out of bed at the sound of his aunt's voice from down the stairs. It was Dudley's turn to make breakfast, that morning; Aunt Petunia was very strict about the distribution of chores in the Evans-Dursley-Potter household, and there was no skiving off, no matter _how_ busy you were.

Dudley was a decent cook. Harry was looking forward to breakfast already as he skittered down the stairs, and grabbed the post on his way to the kitchen.

It was a rather meager pile of post. He shuffled through it, regardless.

A thick cream envelop caught his attention. It wasn't like the other post—it was heavy, somehow, had a weight that Harry didn't have the words to describe.

And it was addressed to him.

There was _never_ any post for him. Not for lack of trying; he didn't have many friends, and Uncle Vernon would never dream of writing Harry a letter. Both of his parents were dead, and had been so for longer than he could remember. There was no one _to_ write him letters.

But there it was, his name written across the envelop, clear as day. The ink was a vibrant emerald green, just near the colour of his eyes.

(There weren't many things that Harry Potter liked about himself, but the colour of his eyes and the thin, lightning-bolt shaped scar on his forehead were two of them.)

"Oi, Harry, there's bacon!"

Harry made a mad dash for the kitchen, the letter clutched tightly in his hand, to find his family sitting around their little wobbly table. Aunt Petunia was sighing morosely, though about what, Harry had no idea—

"Hello, Harry!"

"Uncle Remus! Uncle _Sirius_!" Harry shouted at the top of his lungs, and threw himself on his godfathers. "I didn't know you were back!"

"Harry, sit down, let them breathe," Aunt Petunia said. She was staring peevishly at the mud on Sirius' boots. Sirius pretended not to notice. He was quite good at that, pretending, especially when it made Aunt Petunia's blood pressure rise.

Harry wasn't quite sure how he felt about that.

Because on one hand, Uncle Sirius was the only person who could get away with raising Aunt Petunia's blood pressure without getting promptly shrieked at for the slight. On the other, Aunt Petunia usually had a reason for shrieking, and although Harry didn't know much about blood pressure, he did know that Dudley was always complaining about how much of the weekends he spent at Uncle Vernon's were put towards listening to his uncle whinge about it. It couldn't have been a good thing, and for all that Aunt Petunia was strict and tall and pale as morning mist, she _was_ the closest thing Harry had to a mother, and he did like her very much, and it absolutely wasn't fair to pull her braids the way Uncle Sirius was wont to do.

"Where's Dudley?" Uncle Remus was asking Aunt Petunia.

"He's in detention," Harry piped up.

Uncle Remus' face contorted just as Aunt Petunia's did—it was the exact same face, and if Harry didn't know better, he would have laughed (as it was, Uncle Sirius had to turn away to keep from losing his control, and Harry prided himself on the fact that he had more guff than _that_).

"What happened?"

"It wasn't—" Harry stopped, and then looked up at Aunt Petunia. She was holding her head very still, exactly how she did whenever Uncle Vernon came to get Dudley for his weekends. She didn't have the smile, yet, but Harry could tell that it wouldn't be long before his aunt's lips thinned and pulled into something resembling a smile only in theory, and then she'd lose her temper later when no one was looking and there would be vase shards all over the floor.

(It was just that Harry was always looking, even though the vases were always ugly.)

Telling his uncles what had really happened to have Dudley in detention would be no good, Harry decided. Uncle Sirius would just go try to break him out, because that was what Uncle Sirius _did_ to little boys in detention: he broke them out and bought them ice cream for their misbehaviour. And Uncle Remus would sigh loudly, and go on a long lecture about why he, Harry, needed to stop doing Dudley's homework for him, even if the bullies _were_ all over him.

Aunt Petunia would just hold her head very still, steel all down her spine. She looked even more like a horse when she did this than she did normally. Harry had no desire to inflict that particular look upon the world more than it had to be.

"It was a bad day," Harry said. This was true. It had been a bad day, and Harry's lunch had ended up in the bin, and Dudley's meaty fist had ended up in Ian Milkovich's eye for putting it there, and Dudley had ended up in detention for putting _it_ there.

Aunt Petunia's head inclined a fraction of an inch.

Harry was absurdly proud of himself.

Uncle Remus knelt down and looked Harry in the eye.

"Did you do something, Harry?" he asked, quietly, in that softly probing way of his that had been the undoing of much of Harry's childhood trouble-making. Not even Aunt Petunia's stony silences had been so effective, and this was saying something.

"No, Remus, he did not," Aunt Petunia said, voice clipped as she cut in. "I'll talk to his teachers tomorrow when I bring them to school. Why _are_ you here?"

His Uncles were always off roaming the world for adventures, and were away much of the year. Harry wasn't quite sure why this was the case—Uncle Sirius had the look of money to him, even though Uncle Remus was shabby and often scruffy, there was something distinctly _cool_ about the pair of them when they went off, all leather duster coats and thick boots made for walking.

"Ahh, Pet, can't we come see our favourite nephew?"

Uncle Sirius was, Harry thought sagely, going to get punched.

Harry didn't think his Aunt Petunia had ever punched anyone in her life. He had a sneaking suspicion she was break this record if it meant she could punch Uncle Sirius, just once.

Uncle Sirius really liked to make Aunt Petunia mad.

Uncle Remus stepped between them, just as he always did. "Sirius, not now. Petunia…"

"Not _now_, Remus?" she retorted. "I thought you were in Africa until October."

"Morocco, specifically," Uncle Sirius said cheerfully. "Finished early. Moony here was all hands on deck! I hardly had to do a thing, can you imagine?"

"Stop with the sayings, Black, you're terrible at them," Aunt Petunia said, lips pulled tight. "And go take your boots off, you're getting the floor dirty."

For once, Uncle Sirius did as he was told, and he wandered towards the front door of the flat with his hands stuffed into his pockets, whistling all the while. Both Aunt Petunia and Uncle Remus watched him go; bothered and exhausted respectively, they were.

"Would you like a cup of tea, Remus?" Aunt Petunia said, at last, her voice gentling just the littlest bit, though it sounded like she'd rather it hadn't.

"Yes, please," he said gratefully.

He settled down at the table, shoulders slumping in on themselves. They'd forgotten he was there—it wasn't something they did often, but once in a while, Harry caught a glimpse of who his adults were when he wasn't around. They were tired and old, with lines on their faces that all seemed too deep for people their ages.

His uncles weren't really his uncles. Aunt Petunia had told him that story, how his parents had died and he'd been sent to live with her instead, and how his uncles had been most displeased with the situation. Uncle Sirius had nearly gone to _jail_ for something someone else did. Uncle Remus was always ill.

There was something there, but he couldn't quite put his finger on just what it was.

He'd figure it out eventually.

"Tea?" Uncle Remus asked hopefully.

Harry went to put the kettle on.

—

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	3. half turned to dust

**disclaimer**: disclaimed.  
><strong>dedication<strong>: TO CHLOE BC I WANT HER TO SHIP THIS WITH ME  
><strong>notes<strong>: don't even look at me i ship it so hard

**title**: half turned to dust  
><strong>summary<strong>: Something out of nothing, like a soul. — Petunia/Remus.

—

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Remus takes Harry to King's Cross because Petunia won't.

It is September 1st, and she is losing one of her sons to the same school that took her sister nearly two decades earlier. Dudley doesn't ask—Dudley already knows that Harry is different, that Harry is _special_.

He accepts it with much better grace than she ever did.

She's not surprised about this.

Dudley is not like other children his age. He is bigger and somehow quieter, and, Petunia can admit, not as bright. But he is kind, her boy, always feeding pigeons and stray cats, tall for his age and growing still. He minds the younger children without being asked, walks them to their buses in the morning before he goes to school, his jeans patched at the knees from where he's torn them open defending the littlest ones from school bullies. He is not going to be suited to university, she knows, not the way Harry would have been if he hadn't magic at his fingertips.

Harry is clever and Dudley is kind, and together, they make quite the pair.

"He'll be home for Christmas," she scolds herself aloud. "Lily always was."

Petunia doesn't often think her sister's name, much less _say_ it, but for now she thinks she deserves this. Lily always came home for Christmas, laughing and red-cheeked, deep pockets full of butterflies and chocolate frogs and notes from her friends. She came with sweets Petunia couldn't have named if she tried, and big thick books that smelled of vanilla and silence, if silence had a smell.

And Petunia had never once spoken to her about it.

Lily was gone, and now Harry is, too.

Petunia shakes herself out of it. Regret is for melancholy days, and she does not have many of those. Frankly, she has too much to do—with Harry off to that school, she is going to have to pick up the slack. Dudley's homework would need to be checked, they could do that after supper, after they did the dishes—

A bell rings.

She jerks her head up, eyes narrowing, lips pursing. A strand of ash-blonde hair falls across her vision, and everything slows.

Petunia hadn't been expecting anyone.

There is a bat by the front door. Heavy, wooden, sturdy; it is a pale line of safety at the limit of her home to keep the dark things outside where they belong. Petunia had cause to use it before, but never during the day. She doesn't want to think about the state of the hallway: there has been blood on the walls before and there will be blood on the walls again.

She wipes her hands on a dishtowel, and stalks out of the kitchen, rolling her sleeves up as she goes. The bell's fallen silent, but still she eyes the door suspiciously. Elderly Mrs. Mattheson next door always rings before bringing cookies. No one else would be home, this time of day.

Petunia is not stupid.

She peeks through peep-hole before she opens the door.

The exhale that escapes her moves her entire body.

Remus.

Of course.

She yanks the door open, and glares at him with all her might.

Remus Lupin is a shabby man in a long dusty-brown coat and boots of an indeterminable sort of leather. He is her age, perhaps a year younger; no older than thirty, but the scars across his face make him look older. In fact, everything about him makes him look older, from the lines around his eyes to the nick in his lip. His hair is the colour of wet sand, skin a shade darker, and despite the air of danger that hangs around him like a shroud, he smiles like sympathy.

Petunia can't stand him.

(No, this is a lie. She can stand him. For all his _wizardry_—even in her mind she spits the word—Remus is tolerable to a fault. It is Sirius Black that she cannot stand.)

She opens the door, regardless.

"Lupin," Petunia says colourlessly.

"Hello, Petunia," he says, and his tone is light. His hands are stuffed in his pockets, and he is, there is no other word for it, _lounging_. Something in chest wants to snap at him to strand straight, he's been spending too much time with Black, again, _when_ is he going to learn.

"I didn't think I'd see you until Christmas," she says, the muscles in her face too stiff to even fake a smile. "What do you want?"

"May I come in?" he asks.

Petunia stands there for a moment, the bat within reach. She forgets, sometimes, that there are deeper and darker things out there, things that can't be beaten back with a bat or a sharp tongue. She forgets that there are bits of dirt that can't be scrubbed away.

"I was just about to put the kettle on," she says. "Take your boots off—"

"—you just washed the floor," he finishes for her, smiling.

Petunia's stomach clenches itself into knots as he follows her in. She does not like having people at her back, never has. But Remus, for all he brought Harry away, is one of the few people in the world she trusts not to stab her in her soft places if only because she'd destroy him right back.

"Close the door," she reminds him.

He already has. Petunia breathes a sigh of relief.

The flat is small. They can't afford much more than this, not on her salary (or lack thereof), but it is homey and so clean it shines. There is no excess dirt on the sill where Petunia keeps her potted herbs, no grime in the mortar between the tiles on the floor; everything smells of lemon cleaning supplies, and this is exactly as she likes it.

Remus is careful to keep the dust on his coat from hitting the floor.

Petunia approves. He's right, she did only was the floor this morning. She'd always cleaned as a method of coping, and having it mussed this would be irritating. She's just put the kettle on when it's whistling. There's no way it could have boiled that fast—

She whirls to glare daggers at the man sitting at her table.

"No magic in the house," she says, frostily. "You know the rules."

"Harry's not here," he says, gently.

"The rules are there for a reason, Lupin," she says, as severe as he is gentle. "If he catches you at it, there'll be no stamping the habit out, and I'll have pots and pans doing some sort of ballroom dance on the ceiling."

He's looking at her with level eyes, clear and quiet across the space between them.

"Oh," she says, and narrows her eyes again. "Lupin, have you come to _comfort_ me?"

He stiffens, to her very great satisfaction. "No, I—"

"You're a terrible liar," Petunia cuts him off shortly.

And he sighs, a great exhalation of breath, like he was expecting her to do that. He probably had been; in some ways, Petunia is very predictable. Her regret and her icy temper are two things anyone who knows her can count on.

"Yes," he says. "I wanted to make sure you were alright."

"I'm fine," she says shortly.

He doesn't say that she doesn't sound fine, but then, Remus is much kinder than Petunia knows how to be. He won't call her on the flimsy tremble to her shoulders.

A moment later, Petunia can't keep it in, anymore.

"How do other parents do it?" she asks, voice ragged, tripping over the vowels of a sob. She thinks of Harry, with his big green eyes and his always-crooked glasses and the way he grins when he's gotten into something that he knows no one is ever going to believe. "How do they send—how do they just—?"

"I don't know," Remus says. "I wish I did."

He doesn't move to touch her when she turns away, and for this, Petunia is grateful. He doesn't see the tear in the pit of her eye, the loss like a physical weight. She knows if anyone touched her now, she would break.

Petunia Evans does not have _time_ to break.

She shakes her head, and gives herself two deep breaths in through her nose to calm down. When she turns back to Remus, her eyes are dry.

He's smiling.

"Me, too," he says. "Next time you should come with us. Dudley, too."

It's the mention of Dudley that does it.

Dudley, who is big and slow and sweet. Dudley, who looks at Harry and sees a brother and a best friend. Dudley, who looked his father in the face and told him to _leave my mum alone_. Dudley, who the Wizarding World always seems to forget.

But Remus remembers.

Petunia stills the shaking of her hands by busying herself with pouring a pot of tea. She turns and catches sight of the bump in his throat, imagines pressing her thumb there hard until the blood rushes away and leaves the skin white.

She's shooing the thought away before it has a chance to fully form.

This is Remus.

Remus, who remembers Dudley when no one else does.

The scrap of chair leg against tile rouses her from her thoughts. Remus is standing up, uncertainty in his face for a flicker of a second before it closes off, and she's left looking at a face as stone-cold empty as her own.

"I should go. I just want—"

"Would you like to stay for a cup of tea?" she cuts him off.

He looks at her for a long time, and Petunia would find the regard uncomfortable for the fact that Remus doesn't think her beautiful, and sheis absolutely alright with that. Petuniaiss only beautiful on the surface: she is all sharp angles, hoar-frost flowers on the windows that melt away with the warmth.

Remus Lupin looks beyond the surface.

"I'd like that," he says, hovering still.

"You can sit down, Lupin," Petunia says, lips twisting wryly. "I'm not going to kick you out. I offered tea. I'm not _that_ unpleasant."

(She is that unpleasant, though, and they both know it. He doesn't remind her of the time Sirius stomped all over the flowers growing on the balcony in the back and she got so angry her face went numb from the rage. They'd had so little, and Petunia does so love her flowers.)

So Remus sits down, a little awkward, a little sweet, and he smiles at her.

"Here," she says, and sets the tea down in front of him.

"Are you going to sit?" he asks, indicates the rickety chair next to him. For a moment, she is hit with an image of Harry and Dudley fighting over the chair in the middle, both always wanting to be together but also apart. Something out of nothing, like a soul.

"Yes," says Petunia, softly, nearly smiling back, "I think I will."

And she does.

—

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_fin_.


End file.
